The present invention relates to an expansion joint device, which is used for connecting the ends of metal conduits during laying metal pipelines. More specifically, the present invention relates to an expansion joint device useful for connecting the pressurized medium-conveying pipes, for examples, for connecting the ends of steel pipes used in the water-diversion pipelines of a hydropower station.
For the metal conduits for conveying water, oil, gas or other mediums, especially for those with comparable large or large-size diameters, such as the steel pipes in the water-diversion pipelines of a hydropower station, the pipes can be expanded or contracted by the effects of physical behavior of the conveyed medium and the changes of the ambient temperature during the operation process, and the induced thermal stress may cause the pressurized pipes to be damaged. Therefore, as the metal conduits being laid, expansion joint device need to be provided at the ends of the pipes as being connected to each other.
FIG. 1 shows a currently used expansion joint device for metal conduits. The expansion joint device comprises two short tubes 1xe2x80x2, 2xe2x80x2 and a sleeve 3xe2x80x2. One end of the sleeve 3xe2x80x2 is sealed and connected with the wall of the short tube 1xe2x80x2, and the other end of the sleeve 3xe2x80x2 is engaged with the short tube 2xe2x80x2 on the outer wall surface of the end portion. A sealing ring 4xe2x80x2 is provided in the engaging portion and is fixed by a holding ring 5xe2x80x2 A compensating gap 6xe2x80x2 is set between the opposed inside ends of the two short tubes. As the changes in the axial dimensions of the pipes arise from their thermal deformations, the opposed ends of the two short tubes can axially move to each other, and hence the thermal stresses can be released. Such traditional sleeve-type expansion joint device can have a simple structure, but the short tubes are susceptible to be radially distorted by the effects of the external forces applied during the fabrication and installation processes, and hence the sealing ring 4xe2x80x2 can hardly take its due play of satisfactorily avoiding leakage, especially in the case of conveying the highly pressurized medium. For this reason, in the practical use, water-logging wells need to be prepared below the expansion joint device, and the water leaked into the wells needs to be aperiodically discharged. As a result, the running expenses are increased, and the hidden trouble for safety always exists.
It is therefore an object of the present invention to provide an expansion joint device used for metal conduits with no leakage.
It is another object of the present invention to provide an expansion joint device used for metal conduits, which can avoid leakage of large-size diameter, highly pressurized metal conduits, and has a stable and reliable working performance.
According to the first aspect of the present invention, an expansion joint device for metal conduits is provided, which comprises an inlet short tube, an outlet short tube and a sleeve, the opposed inside ends of said two short tubes are both in the inside of the sleeve and form a compensating gap between them, and wherein a bellows member, axially expansible with an external force applying on, is provided in the compensating gap between the opposed inside ends of the two short tubes, and the two ends of the bellows member are respectively connected to the inside ends of the two short tubes in an sealed manner, at least one of the two ends of said sleeve is free end with respect to the two short tubes.
Because the bellows member in the compensating gap is capable of axially expanding or contracting due to an external force applying on, and its two ends are sealed and connected with the inside ends of the two short tubes, the expansion joint device of the invention can both accommodate the axial dimension changes of the pipes caused by their thermal deformations, to release the thermal stresses, and effectively avoid leakage occurrence so as to prevent safety accidents that may be caused by pipeline leakage.
According to the second aspect of the present invention, an expansion joint device for metal conduits is provided based on the first aspect of the present invention, wherein a trough in a ripply node of the inside-oriented ripple in the bellows member is provided with a trough-mated core, and a gap is formed between the surfaces of the trough and the trough-mated core, and the gap enables the ripply node to be deformed without exceeding its elasticity limit.
According to the third aspect of the present invention, an expansion joint device for metal conduits is provided based on the second aspect of the present invention, wherein an antiwear ring is connected to the inside end of the inlet short tube, and a gap is formed between the other end of the antiwear ring and the inside end of the outlet short tube, and a gap is formed between the outer wall surface of the antiwear ring and the crests of the ripply nodes of the inside-oriented ripple in the bellows member.
Because said trough-mated core is provided, the bellows member can serve as an effective rigid support. And, with the aid of the antiwear ring, the abrasion of inner wall surface of the bellows member by the conveyed medium can be reduced effectively. Accordingly, as being used in large-size and highly pressurized conveying pipelines, the expansion joint device can effectively protect the connecting portion of bellows member itself with the inside ends of the short tubes from damage.
The above and other objects, features, and advantages of the present invention will appear more clearly to one skilled in the art by reading the following detailed specification about the preferred embodiments of the invention in conjunction with the accompanying drawings.